Fluid heat exchange apparatus



May 27, 1941. c. E. LUCKE FLUID HEAT EXCHANGE APPARATUS 4 Sheets-Sheet 1Filed Jan. 11, 1938 INVENTOR.

Char/es E Lucke &8- W

y 27, 1941- c. E. LUCKE 2,243,430

FLUID HEAT EXCHANGE APPARATUS Filed Jan. 11, 1938 4 Sheets-Sheet 2INVENT OR.

Char/e5 5L uck a M ATTORNEY.

y 27, 94 c. E. LUCKE 2,243,430

FLUID HEAT EXCHANGE APPARATUS Filed Jan. 11, 1938 4 Sheets-Sheet 3 INVENT OR.

' cfz af/es E Lucke ATTO'RNEY.

May 27, 1941. c. E. LUCKE FLUID HEAT EXCHANGE APPARATUS Filed Jan. 11,1938 4 Sheets-Sheet 4 INVENTOR. Char/e5 E. Luc'ke I ORNEY.

Patented May 27, 1941 2.243.430 rwm HEAT sxcmncn APPARATUS Charles E.Lucke, New York, N. Y., minor to The Babcock a Wilcox Company, Newark,N. J., a corporation of New Jersey Application January 11, 1938, SerialN0. 184,363

12 Claims.

This invention relates to fluid heat exchange apparatus, and it isparticularly concerned with improvements in heaters which employ spacedtubes for conducting the fluid to be heated.

Where spaced tubes are employed for heating fluids that rise intemperature as they receive heat, and with unequal quantities of fluidin them or with unequal heating effects in different parts of the hotgas spaces occupied by the tubes corresponding inequalities in thetemperature of difierent tubes have resulted and have caused those tubesto expand in different degrees. This. in many cases, has caused some ofthe tubes to move to positions out of their installed alignment and haspresented serious problems in the maintenance of the integrity of suchfluid heaters. This has been particularly true where high temperaturesof the heating gases and high fluid temperatures are involved. Anoutstanding example of this dlfliculty is the experience which has beenencountered in steam superheaters. It is one object of this invention toameliorate such conditions and consequently improve the structure andoperation of such installations.

Another object of the invention is to provide for the accumulation ofash or slag between the water tubes of a water wall of a steam boilerlying in front of a refractory backing to protect the refractory fromdamage that would result from its direct exposure to the furnaceinfluences. It has been a common practice to use straight vertical watertubes in front of refractory furnace walls as a means of reducing damageto the refractory when such damage might result without such furnaceface cooling. With this arrangement there are vertical strips ofrefractory between the water tubes that are exposed to the furnace, andthere have been damages by the combined effect of high temperature andslag. By causing the ash or slag to accumulate between water tubes andin front of the refractory wall, in pockets to prevent downwardmovement, such refractory damage may be prevented, but heretofore nosatisfactory way of meeting the conditions has been found. With thepresent construction providing pockets, refractory may be placed in thepockets instead of waiting for them to fill with ash or slag, and whenso placed it is adequately cooled so as to resist damage.

Another object of the invention is to provide fluid heaters withmultiple tubes so constructed and arranged that adjacent tubes may bewelded at spaced points along their lengths so as to have a "girdereffect. This feature of the invention is particularly advantageous, notonly in wall tubes, but also in high temperature superheaters of theconvection type employing a bank of horizontally disposed tubesextending across the path of the furnace gases. Dueto the higher steamtemperatures which have been employed, the metal temperatures of suchconvection superheaters have become correspondingly high. Tubes are aptto be structurally weakened thereby. Various attempts have been made toovercome this problem but none of them has been completely successful.

Other objects of the invention will appear from the accompanyingdescription when read in connection with the drawings. The latterdisclose structures which illustrate different embodiments of theinvention.

In the drawings:

Fig. 1 is a view in the nature of a sectional elevation indicating amodern steam generating installation burning pulverized fuel andoperating at high furnace temperatures and high steam pressures.

Fig. 2 is a view in the nature of a vertical section through a boilerfurnace fired by an underfeed stoker and involving walls adjacent thestoker.

Fig. 3 is a fragmentary view in the nature of an elevation of adjacenttubes associated with longitudinal flns which extend across theintertube spaces, and, when the tubes are wall tubes, operate to protectthe refractory of the wall structure on the cooler sides of the tubes.

Fig. 4 is a transverse section on the line 44 of Fig. 3.

Fig. 5 is a fragmentary view in the nature of a sectional elevationindicating an embodiment of the invention in which the sinuous tubes areparallel and are provided with metallic studs to be associated with hightemperature refractory material closing the spaces between the tubes.

Fig. 6 is a transverse section on the line 6-45 of Fig. 5.

Fig. 7 is a fragmentary view in the nature of an elevation of a part ofa furnace wall or furnace gas boundary structure indicating anembodiment of the invention in which the adjacent sinuous tubes are sorelated that they provide refractory receiving pockets. These pocketsare so formed that the tubes co-operate with refractory to efiectivelyanchor the refractory in position to resist its displacement into thefurnace.

Fig. 8 is a transverse sectional view on the line 8-8 of Fig. 7.

pockets, or spaces.

Fig. is a transverse section on the line Fig. 11 is a fragmentary viewof a modification of-the invention wherein the sinuous tubes, arearranged in alternation with respect to interposed straight tubes.

Fig. 12 is a transverse section on the line I2I2 of Fig. 11.

Fig. 13 is a view having some of the characteristics of a horizontalsection through a steam boiler employing a convection superheater.

Fig. 14 is a view in the nature of a side elevation of the superheatershown in Fig. 13.

Fig, 15 is a view in the nature of a plan, indieating a differentarrangement of the sinuous tubes in a superheater such as that indicatedin Fig. 13 of the drawings. a

Fig. 16 is a-view showing an embodiment in which reversibly arrangedtubes having straight sections and sinuously formed sections areassociated.

In the drawings, Fig. 1 illustrates a high tem- 5 perature steamgenerating installation in which the illustrative sinuous tubes I0 areemployed in furnace water walls. The furnace is preferably fired bypulverized fuel burners I2 located in a wall of the furnace. In theignition zone of the furnace (and in the zone of the burners) thefurnace wall tubes-are covered by refractory blocks I4. These elementsare known in the art as Bailey blocks)" They are preferably supported bythe tubes and clamped thereon in good heat exchange relation.

The sinuous tubes I0- exposed to the furnace gases in the furnace :wallabove the blocks I4 are shown as having straight tubes I6 alternatingtherewith. Both sets of tubes are preferably secured at their upper endsto the header 20 from which steam and water are normally discharged intothe drum 22.

Below the upper limit of the high temperature furnace zone defined bythe wall blocks I4, the tubes l0 may be straight, and arranged inparallelism with the tubes I6. Both sets of tubes extend to, and areconnected with, a lower header 24 which may receive an adequate supplyof fluid through circulators which connect the headers 20 and 24, andother circulators affording connection with the water space of the drum22.

The furnace walls arranged in positions normal to the plane of the walldefined by the tubes I0 and I6 may be similarly constructed. One ofthese walls includes the upper header 26 connected by Wall tubes 28 andoutside circulators 30 with a lower header 32. An intermediate header 34is interposed when the illustrated hopper bottom furnace is employed.The inclined tubes 30 define one inclined wall of this hopper bottomand, on the opposite side of the furnace, the inclined tubes 30similarly define another wall of the structure. v

The hopper bottom tubes 30 are connected at their lower ends to theheader 40 which is connected by outside circulators 42 to an upperheader 44. The latter is connected by wall cooling tubes 46 to anintermediate header 40, in communication with the tubes 30 at theirupper ends.

The wall tube header 20 is in communication with the drum 22 by means ofthe circulators I0 75 and 52, similar circulators I4 connecting theheader 44 with the drum 22.

In the installation of Fig. 1 of the drawings the furnace gases passupwardly across the tubes It and ll of a boiler slag screen. These tubesreceive their supply of circulating fluid from the lower header 40 whichis in communication with the water space of the drum .22 by means of thedowntakes 02, the header construction 44, and the nipples 00.

The upper ends of the boiler slag screen tubes 50 and 00 are bent so asto have vertical portions communicating directly with the lower sides ofthe header construction ll. Steam and water from this constructionpasses through the risers I2 into the steam and water drum 22.

The header constructions 04 and I0 are connected by a bank of steamgenerating tubes I4 which extend across the path of the furnace gasesabove the slag screen. An upper row of tubes I0 over this bank are bentso as to have vertical portions separating the heating space Into twogas passes I0 and 00, above the horizontally inclined steam generatingtubes. The vertical portions of these tubes are shown as connected to anintermediate header 02 from which the tubes 04 extend vertically andthen horizontally to the drum 22. The vertical portions of the tubes I0and 04 may be used to support the tubes of a convection superheater 00as well as the tubes of'the economizer sections 02 and 04. They may alsosupport the convection heated tubes of the fluid heater 00. Control ofthe division of the furnace gas flow between the two parallel passes I0and 20 and of the total flow is effected by means of dampers I00 in theupper part of the gas pass 10 and similar dampers I02 in the upper partof the gas pass 00.

Fig. 2 of the drawings illustrates an under-feed stoker installation inwhich the furnace walls alongside the stoker are cooled by theillustrated sinuous tubes I04. These wall tubes are horizontallyinclined as to a mean center line, connecting the lower headerconstruction I 00 with the upper header construction I00. These headerconstructions may be connected into boiler circulation by thecirculators III and H2 and other circulators which correspond to someextent with such circulators as those shown in the Fig. 1 installationand described with reference thereto.

The underfeed stoker of the Fig. 2 installation is provided with fueland air feeding mechanism indicated generally at II4, the fuel bedresting upon the stoker base I I6 which has an inclination correspondinggenerally to the inclination of the furnace wall tubes I04. As the fuelis burned, it moves toward an ash pit Ils, the discharge of ash andclinker from this ash pit being controlled by the regulator I20.

The furnace wall at the discharge end of the stoker of the Fig. 2embodiment is a fluid cooled wall having wall tubes I22 connected intoboiler circulation in a manner similar to that of the wall tubes of theFig. 1 installation, above described. Such connections includeappropriate headers such as the bottom header I24 shown in the drawings.

The tubes cooling the wall at the discharge end of the stoker of Fig. 2may be sinuous tubes arranged in such an association with interposedstraight tubes as that shown in Fig. l of the drawings, or these tubesmay be arranged in accordance with other embodiments of the invention.For example, only sinuous tubes may be employed. Their sinuosities maybe parallel,

according to the embodiment of the invention illustrated in Fig. of thedrawings. In that case, the spaces between the tubes will be closed byhigh temperature refractory material mechanically and chemicallyanchored in place and thermally maintained on the tubes by the metallicstuds I30. These studs are preferably welded to the tubes for thepurpose of maintaining good heat transfer relationship between the studsand the tubes.

The Fig. 2 embodiment of the invention may employ sinuous tubes onlyabove the line of the Bailey blocks" I32, the tubes being upright andparallel in the zones in which the blocks are secured thereto.

Figs. 5 and 6 of the drawings show the illustrated sinuous tubesarranged in parallelism with rows of diverging studs welded to andextending from each tube into the inter-tube spaces. When such aconstruction is used as a part of a furnace wall, a high temperaturerefractory material is tamped in place over and around the studs so asto close the inter-tube spaces, the tubes being bare and directlyexposed to the heat of the furnace gases along their parts betweenopposite diverging rows of studs. In other installations, when similarconstructions are used in zones of higher temperature, the studs may bedistributed entirely around the furnace sides of the tubes and the studsand those sides of the tubes entirely covered with the high temperaturerefractory material. For example, such a construction might be used atthe discharge end of the stoker of the Fig. 2 installation, and alongthe lower portions of the tubes I22.

The Fig. 3 embodiment of the invention is one which may be used infurnace wall constructions in certain zones and includes the inclinedwall tubes I40 and I42 with the sinuous tubes I44 interposed. At itshigh points, such as those indicated at I46 and I48, the latter may bewelded to the parallel tubes I40 (the other similar embodiments of theinvention also being contemplated as employing this welded feature whendesired).

Each of the tubes I40 has multiple short metallic fins longitudinallyspaced thereon and preferably welded thereto along their straight edges.These fins I50, I52, and I54 are located respectively between the highpoints I46 and I40 and they close to a considerable extent the spacesbetween the sinuous tubes and the straight tubes, leaving adequatespaces adjacent the sinuous tubes so as to prevent damage during actualoperation of the apparatus in which this embodiment is employed.

When the illustrative sinuous tubes are employed in such relationship asthose indicated in Fig. 7 of the drawings, they may constitute a part ofthe furnace wall structure which is of advantage in anchoring refractoryfurnace wall bodies. The tubes I60-I63, inc., may be welded at such highpoints as those indicated at I65 and I 68, to maintain them in theiroperative wallforming, relationships, and when the tubes arehorizontally Linclined and arranged in superposed relationship theyconstitute a girder which regidifies the wall construction and maymaintain it between two opposite headers without any other structuralsupport, even if quite long in relation to tube diameter so longer spansare possible than otherwise when single tubes act as beams.

In the erection of a furnace in which the Fig. '1 structure is employed,preformed wall blocks I10 and I12 having the flanges I14 and I16 may beforced tightly into the elliptical type openings between adjacent weldsI" or I 80 and sprung into position between the tubes. They will beanchored to the tubes in this manner. Even if this is not done,displacement into the furnace is prevented by the back flanges of therefractory blocks. The small separated refractory blocks are cooled onall edges and so protected against damage.

The invention also contemplates a mode of furnace wall construction inwhich the tubes are first erected as indicated in Fig. '1 of thedrawings and the Insulation material is next placed in position alongthe cooler sides of the tubes. Thereafter, a high temperature refractorymaterial constituting a part of the furnace lining may be tamped intoposition in pockets such as those which are above described as holdingthe preformed blocks I10 and I12. With this mode of construction, and insome temperature zones, the illustrative construction lends itselfadmirably to a combined metal and ceramic refractory wall constructionin which, the ceramic refractory is effectively held in position withoutthe use of such inter-tube studs as those which have been previouslydescribed and this refractory is well cooled by the tubes bounding itsperimeter.

Such constructions as those indicated in'Figs. 9 and 10 of the drawingsmay be employed in such a superheater as that indicated in Figs. 13 and14, it being understood under such circumstances, that the furnace gasesare passing across tubes, and in a direction normal to the plane ofFigs. 9 and 11.

In such a superheater construction as that indicated in Figs. 13 and 14,the tubes I and I82 may correspond to the water and steam risers 12 andthe water downtakes 62 of the installation shown in-Flg. 1 of thedrawings. If this installation is to be particularly related to theinstallation shown in Fig. 13, the tubes I80 and I82 would correspond tothe downtakes 62 and the upright portions of the tubes 16. Steam to besuperheated passes into the lower loops I84 and through the succeedingloops I86 to the superheater outlet header I88, the tubes of these loopsbeing preferably bent in horizontal planes as indicated in Fig. 13 toavoid pockets in which water may lodge in starting. Certain high pointsof the bends of adjoining loops contact with each other and are weldedtogether at such positions as those indicated at I90 and I02 in thedrawings. In this way, the superheater tubes are maintained in theproper spacing and problems of differential expansion in the tubes,resulting from the different temperatures to which they are exposed, aresolved. Furthermore, the drainability of the superheater is maintainedto the desired degree.

With reference to the superheater construction indicated in Figs. 13 and14 of the drawings, it should be understood that not all of the adjacentloop parts in all of the horizontal planes need to be bent asillustrated in Fig. 13 and welded together. Effective maintenance of thesuperheater tubes in their spaced relationship may be effected by soconstructing only a fraction of the total number of loops. That is, thebending of the loops and the welding of the high points of the bendstogether may take place in only two or three horizontal planes, whereasthe number of planes defined by the horizontally aligned looped partsmay be very much larger in number. Furthermore, some of the welds atcontacting bends in one plane may be omitted.

The parts of the superheater. loops arranged in any given horizontalplane maybe bent as indicated in Fig. 15 of the drawings and the high orcontacting points of those bends may be welded together in the mannerthere shown. In this construction, it will be noted that the nodes andanti-nodes of the loops in successive horizontal planes are in staggeredrelationship so as to produce a heating effect which is of advantageunder some gas flow conditions.

The use of the invention eliminates expensive structural provisionswhich have been necessary in the prior art with straight wall tubes.With the latter, it has been necessary to so structurally support andmaintain one of the connected headers so that it was movable under theinfluence of the expansion of the straight tubes. With proper. sinuosityof tubes, both headers may be fixed in place without introduction ofexsessive stresses.

It is within the scope of the invention that the sinuous tubes may beemployed without contact between adjacent tubes, or without weldsbetween' adjacent tubes. However, when the sinuous tubes do have partsin contact which are welded together, a set of these tubes acts like agirder, and, as a unit, it is stiffer than it would be without thewelding. This permits the use of longer tubes of a given diameterwithout excessive sagging and thus eliminates the costly structuralsupporting metal and permits a number of the tubes to serve as a beamand carry the load of other tubes superposed with reference to thetubes. It also permits a set of these tubes, when used as a water wall,to form a direct support for the brick wall above the tubes. In such awelded assembly, such tubes may be used between the sinuous tubes, andwhen drainability is important, this may be maintained by inclining thewhole set of tubes sufliciently with reference to the angle of theindividual bends of the sinuosities.

With reference to Fig. 16 of the drawings, it will be noted that thisconstruction can have the advantage of the girder effect" above referredto. This effect is produced when the high points of some of the bends ofthe curved tubes are welded to the straight sections. This constructionalso has the further advantage that the tubes are uniform in size andshape. It presents a combination of straight and curved tubes in whicheach tube has a straight section and an undulating section, thesesections being reversed as to adjoining tubes when a plurality of thetubes are connected into opposite relationships. This construction maybe used so that the straight tubes run horizontally in some instances.In others, they may be inclined or upright as in water wallconstructions.

While, in compliance with the Federal Statutes, and particularly see.4888 R. S., I have described my invention with reference to certainparticular structures, the invention is not limited to all of thedetails thereof. It is rather of such a scope-that it may be exemplifiedin various combinations of the details taken from the differentembodiments which are illustrated in the drawings. For example, thestructure which is indicated in Fig. 3 of the drawings might be employedwith a stud tube and refractory construction such as that described withreference to Fig. of the drawings. Again, either one of theconstructions indicated in-Figs. 3 and 5, or different combinations ofdetails, some taken from one of these structures, and others taken fromthe other, might be used in such a side wall construction as thatindicated in Fig. 2 of the drawinss. Also, such a water wallconstruction as that indicated in Fig. 1 of the drawings might be.modified in accordance with the details of the structures indicated inFigs. 3, 5, 9, 11, 7, or 16. Further, such refractory closures as thoseindicated in Fig. '7 of the drawings might be used in conjunction withthe embodiment of the invention which is indicated in Fig. 11, or thatshown in Fig. 16. Still further, such convection superheaters as thoseindicated in Figs. 3, 14, and 15 of thedrawings might include some ofthe details of the embodiments indicated in Figs. 1, 3, 11, and 16.

I claim:

1. In a fluid heater, a furnace wall, sinuous wall tubes spaced fromeach other and arranged with their sinuosities so disposed that oppositesurfaces of the tubes throughout their eflective lengths are tangent toparallel planes having a spacing of the diameter of the tubes, meansconnecting the tubes together in a wall assembly, means for connectingthe assembly into a fluid circulation, and means whereby said tubes aresubjected to the heat of furnace gases.

2. A fluid heater including spaced sinuous furnace wall tubes subjectedto the effect of a heating fluid, and means for connecting said tubestogether with their sinuosities and axes in the same plane, adjoiningtubes being rigidly joined at the positions of adjacent and opposinghigh points of the sinuosities.

3. In a fluid heater, a furnace, a plurality of sinuous wall tubessuperposed with reference to each other and supported at their ends,means for connecting said tubes into a fluid circulation, the tubesbeing so arranged that the high points of opposing sinuosities ofadjacent tubes are in contact, and means rigidly joining said tubes atthe contact positions only so that the group of tubes acts as a girder,thus allowing long tubes to be used without necessitating costlysupporting structures intermediate the tube lengths.

4. In fluid heat exchange apparatus, a furnace having a refractory wall,and sinuous wall tubes 50 arranged along the wall of the furnace thattheir corresponding sinuosities are in alignment and oppositelydirected, pockets being thus formed by said corresponding sinuositiesand said wall for the anchorage of refractory wall protecting material.

5. In Iluid heat exchange apparatus, a furnace, a plurality of spacedand parallel straight tubes arranged in alignment along a wall of thefurnace, sinuous tubes arranged alternately with reference to thestraight tubes and having the high points of their sinuositiessubstantially in contact with the straight tubes, and means rigidlysecuring the sinuous tubes to the straight tubes at the positions ofcontact in order that the entire tube wall shall be rigidified.

6. In fluid heat exchange apparatus, a furnace, sinuous tubes arrangedalong a wall of the furnace with the corresponding sinuosities ofadjacent tubes extending oppositely, metallic studs welded to the tubesand extending into the pockets formed by the oppositely extendingsinuosities, and high temperature refractory bodies installed in asemi-plastic condition in said pockets.

7. A fluid heat exchange unit consisting of similar and reversiblyarranged tubes, each tube having a straight portion for a substantialportion of its length and the remaining portion of the tube formed topresent a plurality of sinuosities, the sinuosities of one tube beingarranged adjacent the straight portion of an adjoining tube.

8. In a steam generator, a furnace, a stoker, inclined sinuous walltubes arranged in wall forming alignment so as to define the furnacewalls on either side of the stoker, means rigidly connecting adjacenttubes intermediate their ends so that they may be effective as aconstruction somewhat in the nature of a girder, and means forconnecting said tube into the fluid system of the generator.

9. In a. steam boiler, a furnace, a stoker for firing the furnace,sinuous wall cooling tubes acting as parts of .the furnace walls at thesides of the stoker, means connecting said tubes into the fluid systemof the boiler and supporting the tubes at such an inclination that theywill drain by gravity.

10. In a fluid heater, a furnace, means for burning a slag forming fuelin the furnace, sinuous wall cooling tubes arranged with the planes oftheir sinuosities in the plane of a furnace wall and with thecorresponding sinuous portions of adjacent tubes arranged in oppositionto thereby form pockets for the accumulation of slag, and meansconnecting said tubes into the fluid system of the heater.

11. In a fluid heater, a furnace, sinuous tubes arranged along a wall ofthe furnace with parts thereof exposed as bare metal to the heat of thefurnace and their sinuosities so disposed as to present pocketsreceiving refractory material, and refractory material disposed inpockets between the sinuous tubes and arranged .to present separatedfurnace face areas interspersed with reference to the bare metal exposedby the tubes.

12. In a fluid heat exchange unit comprising, in combination, aplurality of spaced and sinuous cylindrical tubes with .the axes of thetubes and their sinuosities arranged substantially in single planeformation, an inlet header at one end of the unit and rigidly connectedto the corresponding ends of all of the tubes, and an outlet header atthe other end of the unit and rigidly connected to the remaining end ofall of the tubes, the tubes being connected together at theirsinuosities at distributed points throughout the length of the tubes,such connections co-acting with the tubes and headers to form aself-sustaining unit.

CHARLES E. LUCKE.

